1. Field of the Invention
The present invention relates to a reception apparatus, a reception method, a reception program, and a reception system. More particularly, the invention relates to a reception apparatus, a reception method, a reception program, and a reception system whereby signals received in compliance with the DVB-T2 (Digital Video Broadcasting-Terrestrial 2) standard can be demodulated correctly even if spectrum inversion occurs.
2. Description of the Related Art
The DVB-T2 standard is currently worked out as a representative standard for terrestrial digital broadcasting (see “Frame structure channel coding and modulation for a second-generation digital terrestrial television broadcasting system (DVB-T2),” a DVB website updated on Jun. 30, 2008; searched for on May 27, 2009 on the Internet at <URL=http://www.dvb.org/technology/dvbt2/a122.tm3980r5.DVB-T2.pdf>). Terrestrial digital broadcasts based on the DVB-T2 standard utilize the modulation method called OFDM (Orthogonal Frequency Division Multiplexing).
FIG. 1 is a schematic view showing a composition example of a digital signal in compliance with the DVB-T2 standard.
As shown in FIG. 1, the digital signal complying with the DVB-T2 standard (called the DVB-T2 signal hereunder) has two kinds of frames: frames based on the DVB-T2 standard (called the T2 frame each hereunder), and frames in compliance with some other standard than the DVB-T2 standard (called the FEF (future extension frame) part each hereunder), which is to be standardized in the future.
Each frame is headed by a P1 signal. The P1 signal indicates the FFT (Fast Fourier Transform) size of the frame in question, gives information indicating whether the communication method in use is MISO (Multiple Input Single Output) or SISO (Single Input Single Output), and provides information indicating whether the frame in question is an FEF part. If the frame turns out to be a T2 frame, it has its P1 signal followed by a P2 signal and a data signal.